Antenna array



Dec. 12, 1950 ANTENNA Filed Oct.

HIGH F/Ft'G, SOURCE R. A. FELSENHELD ARRAY Patented Dec. 12, 1950ANTENNA ARRAY Robert Arthur Felsenheld, East Orange, N. J assignor toInternational Standard Electric Corporation, New York, N. 1., acorporation of Delaware Application October 3, 1947, Serial No. 777,606

6 Claims.

This invention relates to an arrangement of feeder lines for an antennaarray and in particular to the arrangement of feeder lines to theindividual antennas of a stacked double surface antenna array.

An antenna of the type comprising two elements such as discs, cones orsimilar elements with surfaces arranged to have a peripheral opening inthe plane of radiation has been used. Such antennas are generallyomni-directional with a polarization perpendicular to the surfaces atthe opening. For convenience, these antennas will be herein referred toas double surface dipoles or dipole antennas. A coaxial line feedingsuch an antenna is arranged so that the outer conductor connects to thelower element and the inner conductor extends to connect with the upperelement. When such antennas are stacked one above the other to form avertical stacked array, each antenna is fed by separate coaxialtransmission lines. Concentric line coaxially aligned with the commonaxis of the antennas have been proposed for feeding such arrays. Withsuch a feed the line becomes very cumbersome if a considerable number ofantennas are used. Moreover, it is difficult to supply each antenna withhigh frequency energy of the same power and phase. To avoid this, theantennas may be fed by a separate coaxial line of the same size. Thefeeder lines are then mounted on the outside of the array instead ofaxially inside the array. However, with the feeder lines on the outsideof the array instead of axially inside the array, the symmetry of theradiation pattern is disturbed by reflection or re-radiation of theradiated energy from the lines. This eifect is of the cable distributesthe effect of the cable on the radiation pattern at different azimuths.

For a better understanding of my invention reference is made to thefollowing description taken in connection with the accompanying drawingand its scope will be pointed out in the appended the greater because ofthe vertical polarization.

across the opening between the two Surfaces of a each antenna only onceand in a different sector of the azimuth from the other antennas. Eachfeeder line is terminated at a respective antenna.

The groupings of the cables reduces the effect of the cable due toreflection and the spiralling claims. The single figure of the drawingllliis trates an embodiment of my invention 10]. the feeding of a doublesurface dipole array wherein one surface comprises a disc and the othersurface is a cone and is known as tne disc-cone type.

Referring to the drawing, the antenna array comprises nine antennas 01'the disc-cone type, I, 2, 3, l, 5, 6, t, 8 and 9, vertically stacked.The array is separated into an upper section it of antennas 5, ii, '1,8, 9, and a lower section II of antennas l, 2,3 and 4 by the junctionbox hous ing it WlliCh may contain an impedance matching transformerandthe extra lengths of cable.

Since the upper and lower sections are substantially the same, it willbe necessary only to de-'- scribe the upper section to illustrate theembodiment of my invention.

In the upper section the antennas 5, 6, f, 8 and 9 are rigidly mountedon the flat insulator rings at I3, i i, l5, l6 and H. The insulatorrings are rigidly fastened at spaced points to four vertical poles l3,i9, 20 and 2| that are rigidly mounted in the top plate 22 0f thejunction box housing l2. A top plate 23 at the upper end of the sectionis rigidly fastened to the four poles to hold them in properrelationship to one another.

The antennas l, 2, 3, 4, E, i, 8 and 9 are con nected in parallel by theflexible coaxial feeder lines 24, 25, 26, 21, 28, 29, 30 and 3| to thetransmission line 32 in the junction box housing 12. For cophasalenergization of the antennas the feeder lines are all made equal inlength, the extra lengths which are not extended for the nearerantennas, being contained within the junction box housing. The lengthsof feeders may be chosen to provide other phasing of the energization.The feede line connecting the antenna 5 to the transmission line 32 isin the junction box housing l2 and is not shown. The transmission line32 connects the feeder lines of the disc-cones to a high frequencyenergy source 33.

The feeder lines 28, 29, 30 and 3f are bound together by bands of string34 and extend out of the junction box housing I2 through the hole 35positioned between the poles 20 and 2| and in line with the periphery ofthe insulator it. They are pirally wound around the array and fastenedto pole 20 at a point near the succeeding insulator it. The feed line 28separated from the other 3 lines 29, 30, and 3| at this point andconnects to antenna 6 as shown.

The remaining lines 29, 30 and 3| are continued to be spirally woundaround the array and fastened to the succeeding pole [9 at a point nearthe insulator I5. The lines are held in position by notch 36 ininsulator ring [4. Line 29 separates from lines 38 and 3| and connectsto antenna 'i in the same manner as line 29 connects to antenna 6. Theremaining lines 30 and 3! are spirally wound in a similar mannerconnectin to antenna 8 and 9 respectively.

In this embodiment of theinvention it is seen that the portion of thecable between the junction box housing [2 and the antenna .1 affects theradiation from between the disc and cone of antenna in an azimuthbetween poles 2G,.and2l. The portion of the cable between insulators Hand I5 aifects the radiation from antenna 'l in an azimuth between polesl8 and IE! or substantially 90 from the disturbance, in the radiationpattern of antenna ,6. Each succeeding. antenna is affected in thesucceeding. uadrant so, that the un fi t dradiation from .fOur .of theantenna will minimize thedistortion of the radiation of one of theantenna. Therebythe radiation pattern. over the entire azimuth will beafiected a minimum, amount.

With the antenna array separated into two sections the feeder lines canbe grouped into two separate cables thereby reducing the size of thecable to further reduce the disturbance of the symmetry of the radiationpattern. Considering the lower section, the feeder lines 24, 25, 26 and21 of the lower section of the array are spirally wound in a,similarmanner and so that the radiation pattern of only. two of theantenna of the entire array are affected in the same quadrant. Theantennas 2,1, 3 and ,4 are connected to the feeder ines 24, 25,26 and 21respectively in the same manner that the antennas fth uppe s ti n arconnec edt the feeder lines. The cables 24, 25, Zfi and 21 extend pastantenna 4. The feeder line 21 branches from the cable below the antenna4 and connects to the antenna. Similarly, the other feeder lines extendpast the respective antenna and connect tothe antenna from underneath. vWhile in the example illustrated the main feeder 32 is shown cominginnormalto the antenna junction box housing it is clear thatfor otherstructures this may not be preferred. ,Should the antenna be mountedone. mast, for example, thefeeder 32.may be broughtupthe mast andpositioned spirally aboutthe lower antenna portions in the same manneras the cables as shown. In this case it is preferable that the samepitch and path be followed bythemain cables and the feeder lines.

While I have indicated the pref erred embodiment of my invention, it isapparent thatmy invention is by no means limited to the exact formillustrated, but that many variations may be made in the particularstructure used without departing from the scope of my invention as set.forth inthe appended claims.

What is claimed is:

1. In an array of double surface dipoles mounted vertically above oneanother and spaced a given distance from one another, a feeder systemfor said dipoles comprising a cable mounted at one end of at least aportion of said array, said cable having the same number of lines asantennas in said portion and being in the form of a spiral arrangedabout the outer peripheries of said antennas and cutting across theopening of each antenna once and in different sectors of the azimuth,each line of said cable being branchedfl'om said cable at a respectiveantenna and coupledthereto.

2. In an array of double surface dipoles mounted vertically above oneanother and spaced a givendistance from one another, a feeder system forsaid dipoles comprising a cable mounted at one end of at least a portionof said array, said cable having the same number of lines as antennasinsaid portion andbeinginthe form of a spiral symmetrically advancedabout .the outer peripheries of said antennas from said end and cuttingacross the openingsof the antennas in symmetrically arranged sectors .ofthe .azimuth, each line of said cable being branched from said cable ata respective antenna andcoupled thereto.

3. An array according to claim 1 wherein each line is a coaxial line.

4. An array according to claim 3 wherein the outer conductor of eachline is coupled to the center of one of said surfaces and the innerconductor extends beyond saidone. surface and connects t the othersurface.

5. An array, according to claim v1 wherein each of said doublesurfacedipoles comprises a disc surface and acone surface, said discsurfacebeingpositioned above the apex of the cone surface and normal tothe axisof the cone surface.

6. In an array .Of. double surface dipoles mounted vertically aboveoneanother and spaceda givendistance frornone another, a feeding system forsaid dipoles comprisingtwo cables mounted in an intermediated positionand being in the form of spirals arranged abouttheouter peripheries ofseparate portions of said array in oppositedirections from saidcentralposition, each cable having the same number of lines as antennasin eachrespective separate portion, each line of said cables beingbranched from said cables at a respective antenna andcoupled thereto.

ROBERT ARTHUR FELSENHELD.

REFERENCES GITED The following references are of record in the fileofthis patent:

' UNITED STATES PATENTS Number Name Date 2,086,976 Brown July 13, 19372,350,916 Morrison June 6, 1944 2,368,663 Kandoian Feb. 6, 1943

